A259370 Numbers n such that 1 + sigma(n)^3 + sigma(n)^6 is prime.

1, 2, 7, 19, 24, 28, 29, 38, 39, 45, 52, 59, 80, 97, 98, 101, 104, 114, 116, 122, 135, 146, 152, 158, 162, 177, 196, 197, 199, 203, 204, 209, 211, 220, 224, 232, 239, 242, 246, 261, 277, 284, 286, 290, 296, 298, 334, 358, 365, 389, 397, 415, 443, 444, 445

Offset

1,2

Links

Robert Price, Table of n, a(n) for n = 1..756

OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Maple

with(numtheory): A259370:=n->`if`(isprime(1+sigma(n)^3+sigma(n)^6), n, NULL): seq(A259370(n), n=1..1000); # Wesley Ivan Hurt, Jul 09 2015

Mathematica

Select[ Range[10000], PrimeQ[ 1 + DivisorSigma[1, #]^3 + DivisorSigma[1, #]^6] & ]
Select[ Range[10000], PrimeQ[ Cyclotomic[9, DivisorSigma[1, #]]] &]
Select[Range[500], PrimeQ[Total[DivisorSigma[1, #]^{0, 3, 6}]]&] (* Harvey P. Dale, May 29 2023 *)

Prog

(Magma) [n: n in [1..500] | IsPrime(1 + DivisorSigma(1, n)^3 + DivisorSigma(1, n)^6)]; // Vincenzo Librandi, Jun 27 2015
(PARI) is(n)=my(s=sigma(n)); isprime(s^6+s^3+1) \\ Charles R Greathouse IV, May 22 2017

Crossrefs

Cf. A000203, A259369, A259371.

Sequence in context: A337614 A343908 A100408 * A103034 A038952 A144589

Adjacent sequences: A259367 A259368 A259369 * A259371 A259372 A259373

Keyword

easy,nonn

Author

Robert Price, Jun 25 2015

Status

approved